No, these sites have not really been hacked. At least, not yet. These were submitted by people who like to be clever and witty but who don't really want to launch federal probes by being clever and witty. So they've gone ahead and modified some famous web sites without actually hacking them. Pretty sly, eh?
While it's entirely possible that someone who does one day hack the site in question will simply copy this clever material over, we don't wish to encourage such behavior. But we would like to see more such material submitted to us at hacked@2600.com.
